A bit ago (I'm bad at uploading stuff sometimes) I did a multi art stream with CrimsyCreates and KitsunaOkami! We each did a sketch, passed the sketch around to another artist to be lined, then those lineworks was passed to another person to be colored and shaded. It was a ton of fun especially since we went with an overall Halloween vibe.

Seriously go check out these people!
https://www.twitch.tv/crimsycreates
https://www.twitch.tv/kitsunaokami

You can see the arts in progress in more detail over on the other post; https://www.weasyl.com/~zaezar/submissions/1955588/3-artists-challenge